Coup Atlas Research Database
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09408111950ConspiracyDissident coup

Costa Rica, 1950 — dissident coup conspiracy

Costa Rica (CRI)Central America, AmericasAugust 11, 1950

Event Summary

The dataset records an event coded as a dissident coup conspiracy in Costa Rica on 11 August 1950, during the constitutional presidency of Otilio Ulate, who had taken office in November 1949 after the eighteen-month provisional junta of Jose Figueres handed over power at the close of the 1948 civil war. The young post-war order faced conspiratorial threats from two directions: the exiled supporters of the defeated former presidents Rafael Calderon Guardia and Teodoro Picado, who were sheltered in Nicaragua by the dictator Anastasio Somoza and would mount armed invasions in December 1948 and again in January 1955; and internal right-wing discontent, exemplified by the abortive Cardonazo revolt of April 1949 against the Figueres junta. No discrete documentation of a distinct plot precisely on 11 August 1950 appears in accessible English sources, but it fits the pattern of calderonista exile plotting against the new order.

Costa Rica weathered these threats and consolidated as Latin America's most stable democracy, having abolished its army in 1948.

Researched Details

Researched

Independent research, added record by record. Hover any label for what it means.

Target identified in Coup Atlas research: President Otilio Ulate governed the post-civil-war constitutional order; the calderonista threat persisted from exile
RESEARCHED NAME
Key figures
Otilio Ulate (constitutional president of Costa Rica, target)
Calderon Guardia and Picado (exiled former presidents plotting a return)
Anastasio Somoza (Nicaraguan patron of the calderonista exiles)

Sources

After the 1948 civil war Figueres headed a provisional junta for eighteen months, then handed power to Otilio Ulate as constitutional president under the new 1949 constitution.
SOURCE REVIEWED Wikipedia, Costa Rican Civil War open source ↗
Exiled followers of former Presidents Calderon and Picado, sheltered in Nicaragua, constituted a persistent threat and mounted an invasion attempt in January 1955.
SOURCE REVIEWED U.S. State Department, FRUS 1955-57 vol. VII open source ↗
The right-wing Cardonazo revolt of April 1949, led by the junta's own security minister Edgar Cardona, attempted to overthrow the Figueres junta and was defeated.
SOURCE REVIEWED Wikipedia, Costa Rican Civil War open source ↗
Costa Rica abolished its army in 1948 and signed the Rio Treaty, invoking it when the calderonista invasion came.
SOURCE REVIEWED CrossWorks, The Demilitarization of Costa Rica open source ↗

Editorial Note

No discrete documentation of a coup plot precisely on 11 August 1950 in Costa Rica was found in accessible English sources this session; the entry records the dataset's coding and the verified context of calderonista exile plotting and right-wing discontent against the post-civil-war order, with the specific plot unconfirmed and flagged as context only. The best-documented plots of the era are the calderonista invasions of 1948 and 1955, separate from this coded date. First Costa Rica record in the dataset run.

Cross-Reference

Only one dataset carries it. One of the three reference datasets we check against carries this event; the others do not list it. That is not a contradiction — the datasets cover different periods and use different thresholds — but it means the record has had less outside corroboration.

Identifiers for finding this same event in the other datasets:

Cline Center id
09408111950

How the match is made is described in crossref-report.md.

Outcome and Target

Coup Atlas research identifies the target as: President Otilio Ulate governed the post-civil-war constitutional order; the calderonista threat persisted from exile.

Baseline coding: Plot discovered and disrupted before execution. Recorded leader fate: remained in office; not physically harmed. The baseline file does not name individual targets; researched names are kept in a separate layer.

Baseline Dataset Citation

Cline Center Coup d’État Project Dataset, v2.2.2
Peyton, Buddy, Joseph Bajjalieh, Michael Martin, and Andrea Gerald. 2026. Cline Center Coup d’État Project Dataset. Cline Center for Advanced Social Research. V.2.2.2. February 17. University of Illinois Urbana-Champaign. doi: 10.13012/B2IDB-9651987_V10
⚑ This citation establishes the coded baseline record; use the claim-level sources above for the researched narrative.

Baseline Source-Document Entries

Los Angeles Times

“Costa Rica Cracks Plot; 200 Reported Arrested,” August 13, 1950

New York Times

“Costa Rica Foils Revolt: Uprising Planned by Followers of Calderon Thwarted,” August 13, 1950

The Sun

“Costa Rica Foils Revolution Plot,” August 13, 1950

This is the citation trail carried by the baseline dataset, grouped by outlet and rejoined from the line-wrapped original. Coup Atlas has not independently re-checked every document; read the original before citing a specific claim. URLs the import damaged beyond safe repair are shown as plain text and listed in citations-report.md. How this list is built →

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